| 1. |
- Shi, Xiaobo, et al.
(författare)
-
Optical Energy Losses in Organic-Inorganic Hybrid Perovskite Light-Emitting Diodes
- 2018
-
Ingår i: Advanced Optical Materials. - : John Wiley & Sons. - 2162-7568 .- 2195-1071. ; 6:17
-
Tidskriftsartikel (refereegranskat)abstract
- Light-emitting diodes (LEDs) based on organic-inorganic hybrid perovskites, in particular, 3D and quasi-2D ones, are in the fast development and their external quantum efficiencies (EQEs) have exceeded 10%, making them competitive candidates toward large-area and low-cost light-emitting applications allowing printing techniques. Similar to other LED categories, light out-coupling efficiency is an important parameter determining the EQE of perovskite LEDs (PeLEDs), which, however, is scarcely studied, limiting further efficiency improvement and understanding of PeLEDs. In this work, for the first time, optical energy losses in PeLEDs are investigated through systematic optical simulations, which reveal that the 3D and quasi-2D PeLEDs can achieve theoretically maximum EQEs of approximate to 25% and approximate to 20%, respectively, in spite of their high refractive indices. These results are consistent with the reported experimental data. This work presents primary understanding of the optical energy losses in PeLEDs and will spur new developments in the aspects of device engineering and light extraction techniques to boost the EQEs of PeLEDs.
|
|
| 2. |
- Bai, Sai, et al.
(författare)
-
Colloidal metal halide perovskite nanocrystals: synthesis, characterization, and applications
- 2016
-
Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534. ; 4:18, s. 3898-3904
-
Tidskriftsartikel (refereegranskat)abstract
- Colloidal metal halide perovskite nanocrystals (NCs) have emerged as promising materials for optoelectronic devices and received considerable attention recently. Their superior photoluminescence (PL) properties provide significant advantages for lighting and display applications. In this Highlight, we discuss recent developments in the design and chemical synthesis of colloidal perovskite NCs, including both organic-inorganic hybrid and all inorganic perovskite NCs. We review the excellent PL properties and current optoelectronic applications of these perovskite NCs. In addition, critical challenges that currently limit the applicability of perovskite NCs are discussed, and prospects for future directions are proposed.
|
|
| 3. |
- Bai, Sai, et al.
(författare)
-
Planar perovskite solar cells with long-term stability using ionic liquid additives
- 2019
-
Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 571:7764, s. 245-250
-
Tidskriftsartikel (refereegranskat)abstract
- Solar cells based on metal halide perovskites are one of the most promising photovoltaic technologies(1-4). Over the past few years, the long-term operational stability of such devices has been greatly improved by tuning the composition of the perovskites(5-9), optimizing the interfaces within the device structures(10-13), and using new encapsulation techniques(14,15). However, further improvements are required in order to deliver a longer-lasting technology. Ion migration in the perovskite active layer-especially under illumination and heat-is arguably the most difficult aspect to mitigate(16-18). Here we incorporate ionic liquids into the perovskite film and thence into positive-intrinsic-negative photovoltaic devices, increasing the device efficiency and markedly improving the long-term device stability. Specifically, we observe a degradation in performance of only around five per cent for the most stable encapsulated device under continuous simulated full-spectrum sunlight for more than 1,800 hours at 70 to 75 degrees Celsius, and estimate that the time required for the device to drop to eighty per cent of its peak performance is about 5,200 hours. Our demonstration of long-term operational, stable solar cells under intense conditions is a key step towards a reliable perovskite photovoltaic technology.
|
|
| 4. |
- Bao, Chunxiong, et al.
(författare)
-
A multifunctional display based on photo-responsive perovskite light-emitting diodes
- 2024
-
Ingår i: NATURE ELECTRONICS. - : NATURE PORTFOLIO. - 2520-1131.
-
Tidskriftsartikel (refereegranskat)abstract
- Current display screens are typically only used for information display, but can have a range of different sensors integrated into them for functions such as touch control, ambient light sensing and fingerprint sensing. Photo-responsive light-emitting diodes (LEDs), which can display information and respond to light excitation, could be used to develop future ultra-thin and large screen-to-body ratio screens. However, photo-response is difficult to achieve with conventional display technologies. Here, we report a multifunctional display that uses photo-responsive metal halide perovskite LEDs as pixels. The perovskite LED display can be simultaneously used as a touch screen, ambient light sensor and image sensor (including for fingerprint drawing) without integrating any additional sensors. The light-to-electricity conversion efficiency of the pixels also allow the display to act as a photovoltaic device that can charge the equipment. Photo-responsive metal halide perovskite light-emitting diodes can be used to create a multifunctional display that can function as a touch screen, ambient light sensor and image sensor.
|
|
| 5. |
- Giovanni, David, et al.
(författare)
-
Ultrafast long-range spin-funneling in solution-processed Ruddlesden-Popper halide perovskites
- 2019
-
Ingår i: Nature Communications. - : NATURE PUBLISHING GROUP. - 2041-1723. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Room-temperature spin-based electronics is the vision of spintronics. Presently, there are few suitable material systems. Herein, we reveal that solution-processed mixed-phase Ruddlesden-Popper perovskite thin-films transcend the challenges of phonon momentum-scattering that limits spin-transfer in conventional semiconductors. This highly disordered system exhibits a remarkable efficient ultrafast funneling of photoexcited spin-polarized excitons from two-dimensional (2D) to three-dimensional (3D) phases at room temperature. We attribute this efficient exciton relaxation pathway towards the lower energy states to originate from the energy transfer mediated by intermediate states. This process bypasses the omnipresent phonon momentum-scattering in typical semiconductors with stringent band dispersion, which causes the loss of spin information during thermalization. Film engineering using graded 2D/3D perovskites allows unidirectional out-of-plane spin-funneling over a thickness of similar to 600 nm. Our findings reveal an intriguing family of solution-processed perovskites with extraordinary spin-preserving energy transport properties that could reinvigorate the concepts of spin-information transfer.
|
|
| 6. |
- Giuri, Antonella, et al.
(författare)
-
Ultra-Bright Near-Infrared Perovskite Light-Emitting Diodes with Reduced Efficiency Roll-off
- 2018
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, an insulating biopolymer is exploited to guide the controlled formation of micro/nano-structure and physical confinement of alpha-delta mixed phase crystalline grains of formamidinium lead iodide (FAPbI(3)) perovskite, functioning as charge carrier concentrators and ensuring improved radiative recombination and photoluminescence quantum yield (PLQY). This composite material is used to build highly efficient near-infrared (NIR) FAPbI(3) Perovskite light-emitting diodes (PeLEDs) that exhibit a high radiance of 206.7 W/sr*m(2), among the highest reported for NIR-PeLEDs, obtained at a very high current density of 1000 mA/cm(2), while importantly avoiding the efficiency roll-off effect. In depth photophysical characterization allows to identify the possible role of the biopolymer in i) enhancing the radiative recombination coefficient, improving light extraction by reducing the refractive index, or ii) enhancing the effective optical absorption because of dielectric scattering at the polymer-perovskite interfaces. Our study reveals how the use of insulating matrixes for the growth of perovskites represents a step towards high power applications of PeLEDs.
|
|
| 7. |
- Guo, Yuwei, et al.
(författare)
-
Phenylalkylammonium passivation enables perovskite light emitting diodes with record high-radiance operational lifetime: the chain length matters
- 2021
-
Ingår i: Nature Communications. - : Nature Research. - 2041-1723. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- Perovskite light emitting diodes suffer from poor operational stability, exhibiting a rapid decay of external quantum efficiency within minutes to hours after turn-on. To address this issue, we explore surface treatment of perovskite films with phenylalkylammonium iodide molecules of varying alkyl chain lengths. Combining experimental characterization and theoretical modelling, we show that these molecules stabilize the perovskite through suppression of iodide ion migration. The stabilization effect is enhanced with increasing chain length due to the stronger binding of the molecules with the perovskite surface, as well as the increased steric hindrance to reconfiguration for accommodating ion migration. The passivation also reduces the surface defects, resulting in a high radiance and delayed roll-off of external quantum efficiency. Using the optimized passivation molecule, phenylpropylammonium iodide, we achieve devices with an efficiency of 17.5%, a radiance of 1282.8 W sr(-1) m(-2) and a record T-50 half-lifetime of 130h under 100mAcm(-2). Perovskite light emitting diodes suffer from operational stability, showing rapid decay of performance within minutes to hours after turn-on. Here, the authors investigate how the steric and Coulomb interaction of ammonium passivation molecules with varying alkyl chain length can improve device stability by suppressing iodide ion migration.
|
|
| 8. |
- Kuang, Chaoyang, et al.
(författare)
-
Critical role of additive-induced molecular interaction on the operational stability of perovskite light-emitting diodes
- 2021
-
Ingår i: Joule. - : Cell Press. - 2542-4351. ; 5:3, s. 618-630
-
Tidskriftsartikel (refereegranskat)abstract
- Despite rapid improvements in efficiency and brightness of perovskite light-emitting diodes (PeLEDs), the poor operational stability remains a critical challenge hindering their practical applications. Here, we demonstrate greatly improved operational stability of high-efficiency PeLEDs, enabled by incorporating dicarboxylic acids into the precursor for perovskite depositions. We reveal that the dicarboxylic acids efficiently eliminate reactive organic ingredients in perovskite emissive layers through an in situ amidation process, which is catalyzed by the alkaline zinc oxide substrate. The formed stable amides prohibit detrimental reactions between the perovskites and the charge injection layer underneath, stabilizing the perovskites and the interfacial contacts and ensuring the excellent operational stability of the resulting PeLEDs. Through rationally optimizing the amidation reaction in the perovskite emissive layers, we achieve efficient PeLEDs with a peak external quantum efficiency of 18.6% and a long half-life time of 682 h at 20 mA cm(-2), presenting an important breakthrough in PeLEDs.
|
|
| 9. |
- Kumawat, Naresh Kumar, et al.
(författare)
-
Metal Doping/Alloying of Cesium Lead Halide Perovskite Nanocrystals and their Applications in Light-Emitting Diodes with Enhanced Efficiency and Stability
- 2019
-
Ingår i: Israel Journal of Chemistry. - : WILEY-V C H VERLAG GMBH. - 0021-2148 .- 1869-5868. ; 59:8, s. 695-707
-
Forskningsöversikt (refereegranskat)abstract
- Metal halide perovskite nanocrystals (NCs) have demonstrated great advances for light-emitting diodes (LEDs) applications, owing to their excellent optical, electrical properties and cost-effective solution-processing potentials. Tremendous progress has been made in perovskite NCs-based LEDs during the past several years, with the external quantum efficiency (EQE) boosted to over 20 %. Recently, metal doping/alloying strategy has been explored to finely tune the optoelectronic properties and enhance material stability of perovskite NCs, leading to further improved device efficiency and stability of the obtained perovskite NCs-based LEDs. In this review, we summarize recent progress on the metal doping/alloying of perovskite NCs and their applications in LEDs. We focus on the effects of different metal doping strategies on the structural and optoelectronic properties of the perovskite NCs. In addition, several works on high-performance LEDs based on metal doped/alloyed perovskite NCs with different light emission colours are highlighted. Finally, we present an outlook on employing metal doping/alloying strategies to further improve the device efficiency and stability of LEDs based on perovskite NCs.
|
|
| 10. |
- Qing, Jian, et al.
(författare)
-
Aligned and Graded Type-II Ruddlesden-Popper Perovskite Films for Efficient Solar Cells
- 2018
-
Ingår i: Advanced Energy Materials. - : WILEY-V C H VERLAG GMBH. - 1614-6832 .- 1614-6840. ; 8:21
-
Tidskriftsartikel (refereegranskat)abstract
- Recently, Ruddlesden-Popper perovskites (RPPs) have attracted increasing interests due to their promising stability. However, the efficiency of solar cells based on RPPs is much lower than that based on 3D perovskites, mainly attributed to their poor charge transport. Herein, a simple yet universal method for controlling the quality of RPP films by a synergistic effect of two additives in the precursor solution is presented. RPP films achieved by this method show (a) high quality with uniform morphology, enhanced crystallinity, and reduced density of sub-bandgap states, (b) vertically oriented perovskite frameworks that facilitate efficient charge transport, and (c) type-II band alignment that favors self-driven charge separation. Consequently, a hysteresis-free RPP solar cell with a power conversion efficiency exceeding 12%, which is much higher than that of the control device (1.5%), is achieved. The findings will spur new developments in the fabrication of high-quality, aligned, and graded RPP films essential for realizing efficient and stable perovskite solar cells.
|
|
